The present invention relates to a work vehicle having an oil cooling path through which a working oil within the transmission housing for a hydraulically driven transmission means is circulated to the transmission case through the cooler.
In the work vehicle of this type, when considering the flow of a working oil to be circulated from the transmission housing to the transmission case through the cooler, particularly at a cold district or in a severely cold season, the temperature of such working oil becomes low and the viscosity resistance becomes large. Accordingly, the working oil cannot smoothly be flowed in the oil path, resulting in the abnormal rise in the internal pressure in the transmission housing. This presents inconvenience to possibly provoke a trouble such as an oil leak.
In order to restrict such abnormal rise in the internal pressure in the transmission housing occurred when the temperature of the working oil becomes low, it may be proposed to use large-diameter pipes for the oil cooling path and to form the cooler into a large size. However, such structure has a defect in that it is necessary to form piping facilities of a large size and subsequently the costs of equipment, operation and maintenance become expensive.